DESCRIPTION: Diseases of the nervous system are among the most devastating and burdensome of all human illnesses, yet they remain among the most poorly treated. For most CNS disorders, we understand the underlying biology poorly, and validated therapeutic targets have not been identified. Ironically, the most druggable protein classes in the genome are highly represented in the nervous system and contribute to the pathology of nervous system disorders. If their nervous system functions were better understood, some would undoubtedly be excellent therapeutic targets. Unfortunately, it remains quite challenging to assign functions to these poorly characterized genes, especially those involved in the complex workings of the CNS. Cell-based, in vitro assays are wholly inadequate to model the functions of genes in the nervous system. Scalable, affordable approaches are needed for systematically disrupting gene function in vivo and assessing the effects on the nervous system broadly. Zebrafish provide a unique opportunity to illuminate the genes of the druggable genome. Over the past five years, new tools have made it possible to make targeted changes in the zebrafish genome. Simultaneously, twelve new behavioral assays have been developed that can assess broadly the effects of genes or small molecules on the nervous system. This project combines these novel techniques for genome manipulation with high-throughput behavioral profiling to characterize genes of the druggable genome. Genes of interest will be knocked out in zebrafish using CRISPR-Cas systems, and the mutant animals will be subjected to a comprehensive panel of behavioral assays to assess effects on the nervous system. In parallel experiments, the same genes will be replaced in the zebrafish genome by a novel visualization/ablation cassette, enabling detailed 4D visualization of the in vivo expression patterns. Finally, a unique computational resource will enable facile identification of candidate ligands (probes) for the proteins of interest. These proof- of-concept experiments will focus on 15 genes selected to include both well- and poorly-characterized examples and will pave the way for a more comprehensive exploration of the druggable genome. Aims include: Aim 1. To characterize the nervous system functions of genes in the druggable genome. Aim 2. To develop tools for visualizing and manipulating the genes of the druggable genome. Aim 3. To identify candidate ligands for genes in the druggable genome. By providing detailed knock-out phenotyping, in vivo expression patterns, and a small molecule probe for each of the genes of interest, we hope to advance the important goal of illuminating the genes of the druggable genome.